An air intake structure of an engine sometimes has a supercharger increasing the amount of intake air into the engine to improve the output of the engine. The temperature of the intake air compressed by the supercharger is increased. Consequently, the engine cannot obtain a sufficient output and is likely to cause knocking. Therefore, as described in Patent Document 1, when the air intake is compressed by the supercharger, an intercooler for cooling the intake air is typically provided on the air intake downstream side of the supercharger.